<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML3.2 EN">
<HTML>
<HEAD>
<META NAME="GENERATOR" CONTENT="DOCTEXT">
<TITLE>MPI_Errhandler_get</TITLE>
</HEAD>
<BODY BGCOLOR="FFFFFF">
<A NAME="MPI_Errhandler_get"><H1>MPI_Errhandler_get</H1></A>
Gets the error handler for a communicator 
<H2>Synopsis</H2>
<PRE>
int MPI_Errhandler_get(MPI_Comm comm, MPI_Errhandler *errhandler)
</PRE>
<H2>Input Parameter</H2>
<DL><DT><B>comm </B> <DD> communicator to get the error handler from (handle) 
</DL>
<P>
<H2>Output Parameter</H2>
<DL><DT><B>errhandler </B> <DD> MPI error handler currently associated with communicator
(handle) 
</DL>
<P>
<H2>Thread and Interrupt Safety</H2>
<P>
This routine is thread-safe.  This means that this routine may be
safely used by multiple threads without the need for any user-provided
thread locks.  However, the routine is not interrupt safe.  Typically,
this is due to the use of memory allocation routines such as <TT>malloc
</TT>or other non-MPICH runtime routines that are themselves not interrupt-safe.
<P>
<H2>Notes for Fortran</H2>
All MPI routines in Fortran (except for <TT>MPI_WTIME</TT> and <TT>MPI_WTICK</TT>) have
an additional argument <TT>ierr</TT> at the end of the argument list.  <TT>ierr
</TT>is an integer and has the same meaning as the return value of the routine
in C.  In Fortran, MPI routines are subroutines, and are invoked with the
<TT>call</TT> statement.
<P>
All MPI objects (e.g., <TT>MPI_Datatype</TT>, <TT>MPI_Comm</TT>) are of type <TT>INTEGER
</TT>in Fortran.
<P>
<H2>Note on Implementation</H2>
<P>
The MPI Standard was unclear on whether this routine required the user to call
<TT>MPI_Errhandler_free</TT> once for each call made to this routine in order to
free the error handler.  After some debate, the MPI Forum added an explicit
statement that users are required to call <TT>MPI_Errhandler_free</TT> when the
return value from this routine is no longer needed.  This behavior is similar
to the other MPI routines for getting objects; for example, <TT>MPI_Comm_group
</TT>requires that the user call <TT>MPI_Group_free</TT> when the group returned
by <TT>MPI_Comm_group</TT> is no longer needed.
<P>
<H2>Errors</H2>
<P>
All MPI routines (except <TT>MPI_Wtime</TT> and <TT>MPI_Wtick</TT>) return an error value;
C routines as the value of the function and Fortran routines in the last
argument.  Before the value is returned, the current MPI error handler is
called.  By default, this error handler aborts the MPI job.  The error handler
may be changed with <TT>MPI_Comm_set_errhandler</TT> (for communicators),
<TT>MPI_File_set_errhandler</TT> (for files), and <TT>MPI_Win_set_errhandler</TT> (for
RMA windows).  The MPI-1 routine <TT>MPI_Errhandler_set</TT> may be used but
its use is deprecated.  The predefined error handler
<TT>MPI_ERRORS_RETURN</TT> may be used to cause error values to be returned.
Note that MPI does <EM>not</EM> guarentee that an MPI program can continue past
an error; however, MPI implementations will attempt to continue whenever
possible.
<P>
<DL><DT><B>MPI_SUCCESS </B> <DD> No error; MPI routine completed successfully.
</DL>
<DL><DT><B>MPI_ERR_COMM </B> <DD> Invalid communicator.  A common error is to use a null
communicator in a call (not even allowed in <TT>MPI_Comm_rank</TT>).
</DL>
<DL><DT><B>MPI_ERR_ARG </B> <DD> Invalid argument.  Some argument is invalid and is not
identified by a specific error class (e.g., <TT>MPI_ERR_RANK</TT>).
</DL>
<P><B>Location:</B>errhandler_get.c<P>
</BODY></HTML>
